The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A variety of structures being joined often require one-sided joining techniques in order to create efficient assemblies. One such technique for one-sided joining is flow-drill screwing (FDS) where a threaded fastener is screwed into a joint and the “nut” is created in situ during the insertion process. When installing a flow-drill screw in thick materials or dissimilar materials, a clearance hole can be used. In addition, with thick gauge material stack-ups, or when a top layer of sheet metal is thicker than a governing size (e.g., >2 mm), a clearance hole can be used in the top layer of the material.
Often times, an adhesive is used in conjunction with a flow-drill screw. When using an adhesive in a joint, there is concern of torque fall-off. Torque fall of is also a concern when using polymer based substrate materials. Torque fall-off occurs where the torque may relax after the joint is tightened to a specific torque. After the joined parts go through paint processes and the adhesive cures, there may be a concern that the torque has changed in the joint.
This torque fall-off issue in joined assemblies, among other mechanical joining issues, is addressed by the present disclosure.